fix tcp forwarding crash

cmd/gost/vendor/github.com/ginuerzh/gost/forward.go

@@ -51,7 +51,7 @@ func (s *TcpForwardServer) ListenAndServe() error {
 
 		select {
 		case <-quit:
-			if s.Base.Chain.lastNode.Transport != "ssh" {
+			if s.Base.Chain.lastNode == nil || s.Base.Chain.lastNode.Transport != "ssh" {
 				break
 			}
 			if err := s.initSSHClient(); err != nil {
@@ -429,7 +429,7 @@ func (s *RTcpForwardServer) Serve() error {
 		glog.V(LINFO).Infof("[rtcp] %s - %s", laddr, raddr)
 
 		lastNode := s.Base.Chain.lastNode
-		if lastNode.Transport == "ssh" {
+		if lastNode != nil && lastNode.Transport == "ssh" {
 			s.connectRTcpForwardSSH(conn, lastNode, laddr, raddr)
 		} else {
 			if err := s.connectRTcpForward(conn, laddr, raddr); err != nil {

cmd/gost/vendor/vendor.json

@@ -21,10 +21,10 @@
 			"revisionTime": "2017-01-19T05:34:58Z"
 		},
 		{
-			"checksumSHA1": "8JlPLyEAjSN5tknRlRClQIVD5XA=",
+			"checksumSHA1": "iO+jPih44pGmJmhxHniw6feeIUA=",
 			"path": "github.com/ginuerzh/gost",
-			"revision": "2ca2bf71871e271ad2b69f7b26e14983c99efc5d",
-			"revisionTime": "2017-02-25T14:51:33Z"
+			"revision": "d5e4e24e8354da5cef62733a4aa8a9d92556945e",
+			"revisionTime": "2017-02-26T10:31:07Z"
 		},
 		{
 			"checksumSHA1": "+XIOnTW0rv8Kr/amkXgMraNeUr4=",

forward.go

@@ -51,7 +51,7 @@ func (s *TcpForwardServer) ListenAndServe() error {
 
 		select {
 		case <-quit:
-			if s.Base.Chain.lastNode.Transport != "ssh" {
+			if s.Base.Chain.lastNode == nil || s.Base.Chain.lastNode.Transport != "ssh" {
 				break
 			}
 			if err := s.initSSHClient(); err != nil {
@@ -429,7 +429,7 @@ func (s *RTcpForwardServer) Serve() error {
 		glog.V(LINFO).Infof("[rtcp] %s - %s", laddr, raddr)
 
 		lastNode := s.Base.Chain.lastNode
-		if lastNode.Transport == "ssh" {
+		if lastNode != nil && lastNode.Transport == "ssh" {
 			s.connectRTcpForwardSSH(conn, lastNode, laddr, raddr)
 		} else {
 			if err := s.connectRTcpForward(conn, laddr, raddr); err != nil {